Gyroscopes (or gyros, where the term is generically used here to refer to angular rate, turn rate, or turn speed sensors) have been suggested to be included in consumer electronics personal mobile devices such as multi-function cellular phones and smart phones. In such a multifunction handheld portable device, the gyro may be used by applications that measure heading changes (for example, in-the-field of navigation) or for measuring the rate of rotation as may be needed by a video game application. The types of gyro that are practical or suitable for use in such devices include micro electromechanical system, MEMS, type vibratory gyros. A MEMS vibratory gyro is particularly suitable for use in a handheld device, because of its relatively small size, low power consumption, suitability for high volume manufacture and low cost. However, such a gyro may be particularly sensitive to temperature, in that its turn rate output signal (indicating the sensed rate at which the gyro package is rotating about a given axis) exhibits significant fabrication process variation as well as temperature variation.
The gyro can be calibrated for zero rate offset during manufacturing test, as follows. The gyro is kept motionless in a temperature-controlled environment. Its output is then sampled and recorded at different temperatures. This offset data is then stored in a lookup table, together with the associated temperature values at which they were collected. The table is then provided with the gyro to a system manufacturer who integrates them into a personal mobile device. A calibration process in the mobile device can then periodically read a temperature sensor that may be integrated with the gyro, lookup the associated offset correction from the table, and then apply the correction to the output of the gyro.